Acromioclavicular joint dislocations usually involve a severe displacement of the lateral end of the clavicle relative to the acromium of the scapula. Treatment of complete acromioclavicular joint dislocation is still very controversial. It ranges from rehabilitation to extensive surgical reconstruction. However, high-grade injuries (type IV, V, and VI) are typically treated surgically.
Most reconstruction techniques addressing these injuries selectively focus on coracoclavicular ligament augmentation because it has been shown a primary stabilizer of the acromioclavicular joint. The main problems in the clinical routine of coracoclavicular polydioxanone (PDS) loop augmentations are highly invasive preparation of the coracoid base and anterior subluxation of the clavicle causing malreduction of the acromioclavicular joint post operatively. Furthermore, the synthetic materials used for coracoclavicular cerclage have been detected to saw through the lateral clavicle and the coracoid as a result of rotational motion of the clavicle. On the other hand, rigid acromiclavicular joint fixation, using such techniques as the Bosworth screw or C-hook implants, leads to overstiffening of the joint and further complications, such as implant breakage and implant migration. A common disadvantage of all of these techniques is that they are highly invasive and are associated with corresponding postoperative morbidity.
Recently, minimally invasive arthroscopic techniques have been developed in order to reduce morbidity during the rehabilitation period and to improve surgical outcome. One advantage of suture anchors is that they can be placed at or close to the insertion site of the coracoclavicular ligaments. Therefore, the augmentation can imitate the course of the coracoclavicular ligaments more closely than can a PDS cerclage that is placed around the coracoid. However, most known suture anchors are primarily developed for connecting a soft tissue to a bone. In contrast, coracoclavicular augmentation means anchoring bone to bone. The length of the suture loop connecting both bones required for coracoclavicular ligament augmentation differs significantly from the direct bone to tendon contact achieved by other procedures. Furthermore, the coracoid suture anchor has to withstand much higher stress than the anchors used in other procedures.
A new technique that reduces the above complications by replicating the orientation of the native coracoclavicular ligament complex has been described in Wellmann, M., Zantop, T., Peterson, W., “Minimally Invasive Coracoclavicular Ligament Augmentation With a Flip Button/Polydioxanone Repair for Treatment of Total Acromioclavicular Joint Dislocation,” Arthroscopy 2007, which is incorporated herein by reference. This technique provides a minimally invasive subcoracoid and clavicular fixation of a double PDS loop by use of two flip buttons or anchors, typically used for extracortical anterior cruciate ligament graft fixation.
Metal anchors or buttons are commonly used for fixation of grafts during the anterior cruciate ligament reconstruction surgery. Usually, the ruptured ligament is removed and drill-holes are made into close vicinity of the original insertion cites of the anterior cruciate ligament. Then, a replacement graft, which can be either a natural or a prosthetic ligament, is pulled through and fixed into the drill-holes using the anchors, thus replacing the ruptured ligament. The common technique for moving the anchor though the drill-hole in the bone is to use a thread which is fixed to the anchor to pull the anchor out. Such technique has been described, for example, in U.S. patent application No. 2007/0016208 to Thornes. In the method disclosed in Thornes, a suture is passed upwards through a drill hole in a bone and then is passed through an open surgical wound. This pull-through suture, which engages an aperture of a button (anchor), can then advance the button through the drill-hole. The disadvantage of such method is that, in addition to a main incision through which the replacement graft with anchors is introduced, a second access is required in order to pass the anchor through the opening in the bone. Accordingly, such method is more invasive and, thus, more traumatic to a patient undergoing the procedure.
In view of the above described shortcomings of the prior art devices, there is a need for improved devices, instruments and surgical methods used in replacing and reconstructing torn or dislocated ligaments so as to make the process more efficient and effective, and, at the same time, less traumatic to the patient.